I built a MLT using a 5 gal cooler that I already had using FlyGuy's instructions from here. The only difference is I used a Tee Fitting and created a loop with the stainless braid.

From the instructions it seems like people are saying that 12 lbs of grain is about the max for this design. Looking at Northern Brewer at their 5 gal all-grain setup they are using the same coolers but with a false bottom instead of the stainless braid. They claim that their cooler maxes out at 15 lbs of grain.

Looking through their kits as an idea of how much grain to expect for different styles, it appears that I can get by with my current setup if it maxes out at 15 lbs but if it maxes out at 12 I will have to upgrade to a 10 gal cooler.

BTW I'm starting out with batch sparging...

I know eventually I will end up with the 10 gal cooler conversion, but right now all I need to go all grain is a wort chiller. I can't afford to go all grain yet if I have to purchase BOTH the chiller and the cooler.

So, for those of you with 5 gal coolers, what is your max grain bill? Does the braid vs. false bottom make a difference in capacity?

I think the difference in grain capacity is going to come from how thick/thin you mash more than the type of filtering item you have at the bottom.

I will add that I have a 10 gallon round cooler, and with appx 22 lbs of grain it it, it's pretty damn full. My grian bill is only that large when doing 10 gallons batches, but I am not able to batch sparge with one single water addition... I have to split the sparge water in half and do two smaller rinses.

I've gotten 13.5lbs in my 5 gal cooler with copper manifold before. Yea it was full but I could have fit a little more in there if I needed to. Over 75% eff as well so no worries about having to thick of a mash.

The largest I've done in my 5 gallon rubbermaid was EdWort's Robust Porter - 13 pounds, 13 ounces. Worked out to about .9 quarts liquid/pound of grain. One thing to keep in mind is the lid on a rubbermaid screws on to the top and the Igloo lid pushes down inside, displacing some of the volume. Mine has a false bottom.